Collector brush clip



Sept. 26, 1944. J. 1'. BROWN COLLECTOR BRUSH CLIP Filed March 20, 1943 Patented Sept. 26, 1944 UNITED STATES PATENT OFFICE COLLECTOR BRUSH CLIP John T. Brown, Berkeley, Calif.

Application March 20, 1943, Serial No. 479,865

8 Claims.

My" present invention relates to commutator brushes or collectors for dynamo-electric machines, and more particularly to an improved pigtail attaching means for carbon brushes that will permit a renewal of the brush by merely replacing the carbon portion thereof.

An object of the invention is to provide an improved carbon brush for dynamo-electric machines having a removable pig-tail carrying clip which will permit a renewal of the brush without a discarding of the expensive pig-tail and its attaching means.

Another object of the invention is to provide a pig-tail attaching means for a renewable carbon brush that will insure a substantially uniform distribution of the collected current throughout the width and thickness of the brush.

Another object of the invention is to provide an adjustable means by which a pig-tail may be connected to carbon brushes of different thicknesses.

In the art to which this invention relates it has generally been the custom to permanently secure the pig-tails to the brushes by securing the pig tail to a cap which is in turn soldered to a tinned or plated end of a carbon brush. With this arrangement, when the brushes are renewed, it has of necessity also been the custom to discard the pig-tail and its connecting means with the brush. This has greatly increased the cost of replacing brushes upon a dynamo-electric machine and is wasteful of the more expensive elements that go to make up the completed brush.

In other instances, where means have been provided for detachably securing the pig tail to a brush, resort has been had either to rivets, threaded screws or expansible plugs which are extended into or through the brush, and in these cases, due to the nature of the attachment, the distribution of the current is more or less concentrated at the points where these rivets, screws or plugs are located upon the brush. It is, therefore, a further object of the invention to overcome the last above difiiculty by providing a. pigtail attaching clip that will give a distributed and maximum of contact surface between the pig-tail attaching means and the carbon portion of the brush and thus result in a substantially uniform distribution of current throughout the width and thickness of the brush when the same is in operation.

Other objects and advantages of the invention will be in part evident to those skilled in the art and in part pointed out hereinafter in the following description taken in connection with the accompanying drawing, wherein there is shown by way of illustration and not of limitation preferred embodiments thereof.

In the drawing;

Figure 1 is a perspective view showing a carbon brush equipped with a pig-tail and attaching means constructed in accordance with a preferred embodiment of the invention,

Figure 2 is a similar view showing the pig-tail attaching means illustrated in Figure 1,

Figure 3 is a perspective view showing a modification of the carbon brush illustrated in Figure 1,

Figure 4 is a fragmentary view showing a modified detail of the invention,

Figure 5 is a fragmentary sectional view showing a brush constructed in accordance with this invention as mounted in a brush holder and in contact with the surface of a commutator,

Figure 6 is a side view showing a modification of the invention as applied to a smaller square brush, and

Figure 7 is a perspective view showing a modified form of pig-tail attaching means constructed in accordance with another aspect of the invention.

Upon referring to Figures 1, 2 and 3 of the drawing it will be seen that the collector brush, constructed in accordance with the present invention and in its preferred form, is comprised essentially of three principal parts; namely, a brush In of carbon or other type of arc resisting material, a clip or saddle-like member I I, and a pig-tail or flexible current carrying connection l2 which is permanently attached to the saddlelike member I I. In Figure 1 the brush I0 is shown as of carbon and as having two oppositely arranged semi-cylindrical grooves l3 cut in the opposite sides thereof which extend laterally across the width of the brush Ill. The grooves I3 are also here shown as having a plated or metallic surface I4 which is applied thereto only over that surface immediately in and around the grooves l3. As a modification of this feature, Figure 3 shows the brush [0 as having a metallic coating or plating [5 which extends entirely over the semi-cylindrical grooves I3 and also the upper end of the brush Ill. This metallic coating or plating I5 and the plated or metallic surface H, as shown in Figures 1 and 3, may be applied by electroplating, spraying, or by merely dipping the brush in a suitable tinning or plating bath. As is better illustrated in Figure 2 of the drawing, the saddle-like member or clip II has downwardly depending sides I 6 which have their lower ends rolled inwardly so as to form involute flanges ll that are adapted to engage the brush ID within the semi-cylindrical grooves l3. The sides l6 of the saddle-like member II are also shown as provided with slots l8 that extend upwardly in the sides thereof a distance sufiicient to provide a plurality of resilient finger-like portions which will insure a more uniform contact between the carbon brush I and the metallic saddle-like member H to which the pig-tail or flexible connection I2 is soldered,.welded or otherwise permanently attached. This saddle-like member H may be made of any suitable resilient material; In its preferred form it will be constructed of tempered beryllium copper, as this material has been found to give sufficient resilience without a sacrifice in the current conducting capacity of the brush as a whole. It is conceivable, however, that the saddle-like member I I may be made of other materials. For example, it may be constructed of spring steel, heavily coated with a good current: conducting metal, such as copper. By the use of tempered beryllium copper a good spring action can be obtained, and when the grooves I 3 are proportioned in depth and contact area with respect to the current carrying capacity of the brush ID, a uniform distribution of the current will be obtained throughout the width and thickness of the brush and, consequently, a'better collection and commutation willresult. At the same time, the saddle-like member or clip ll formed in this manner will act as a thermal-conductor that will radiate heat from the brush. In addi-' tion to the above enumerated advantages, the present invention also provides a construction" by which the wearable or carbon portion of a collector may be readily renewed without a discarding of the copper pig-tail and its attaching means, as'has been thepractice in the past, and, as aresUlt, a considerable saving is'effected' when the brushes l0 are required to be replaced.

While the saddle-like member H is shown as having involute flanges l1 formed at the ends of its depending sides 16, it will be understood that these flanges may take other forms. As shown in Figure 4 of the drawing, these flanges, designated by the numeral l9, are shown as triangular in cross-section and as adapted to engage V-shaped' grooves 29 that are formed in the sides of the carbon brush H]. With the semi-cylindrical grooves [3' or the V-shapedgrooves 20 extending completely across the width of the brush [9 in the manner shown, it will be apparent that the saddle-like member I I can be easily slid intop'osition upon the brush 10 without any substantial flexing of its sides I6. Therefore, the saddlelike member H can be' of a relatively stiff construction, as its sides IE will only be required to flex sufliciently to clear the brush when being applied. An advantage of this" type of construction is that the sides 16 of the saddle-like member I I can be made to establish a high contact pressure between the flanges I! or I9 and the tinned 0r plated surfaces of the grooves l3 or 20 in the brushes l0.

As is illustrated in Figure of the drawing, the sides N5 of the saddle-like member H are recessed within the limits of the sides of the brush 1 B so that when the brush is mounted in a brush holder 2 I, as here shown, the saddl'e-like'inember H will extend downwardly over the sides of the brush a distance suficient to be encompassed by the brush holder 2| where it will not interfere with the free upward and downward movements of the brush l9 when the same ism operation.

At the same time, the sides It of the saddle-like member II will prevent any notching of the carbon brush In which might interfere with its downward movement due to wear.

In Figure 6 of the drawing there is shown a modification of the invention which, it is believed, will find considerable application upon carbon brushes of the smaller types, such as are used with vacuum cleaners and other small fractional horse-power motors. In this arrangement the flexible connection or pig-tail I2 is shown as permanently connected to a cup-like member 22 of resilient material having an annular wall 23 that is provided with spaced slots 24 which will form a plurality of finger-like extensions 25 that are adapted to extend downwardly over a reduced cylindrical extension 26 formed at the upper end of a square or rectangular brush carbon 21. In this arrangement the lower ends of the fingerlike extensions 25 are shown as rolled inwardly so as to engage and make contact Within an annular groove 28 formed at the juncture between the cylindrical extension 26 and the, square or rectangular portion of the brush carbon 27.

In Figure 7 there is illustrated a further modification of the invention which is designed particularly to reduce the cost of maintaining a stock of pig-tail attaching clips or saddle-like members for different size brushes, such as are contemplated by the present invention. In this modification of the invention the clips or saddle-likemembers are shown as formed of two parts 29 and 39 that are adjustable with respect to each other so that the saddle-like member or clip may be adapted for use with renewable brush portions having different dimensions which may vary in thickness. As here shown, the part 29 has a downwardly depending side 3!, and the part 30 has a downwardly depending side 32. These dependingsides 3| and 32 are also provided with" inturned or involute flanges 33 that correspond generally to the flanges ll of the saddle-like member ll. Like the side portion 16' of thesad'dl'e like member II, the side portions 3i and 32 are slotted, as at 34. This will divide the sides 3| and 32 into two finger-like portions and will" insure' a uniform and more perfect contact between the removable brush portion and" the saddle-like member when the latter is assembled upon the brush. The part 29 is shown as provided with a plurality of spaced openings 35 inits top surface adjacent its depending side 3f through which offset tongues 36 carried by the part 30 are adapted to extend, and at its outer end it has a relatively longer slot 31 through;

which an upstanding loop 38 formed upon the part 30 is adapted to extend. The openings 35 of the part 29 permit the parts 29 and 39 tobe" secured together with their Sides- 3! and 32 atdifferent distances from each other, as for example, in increments of one-eighth to one-fourth inch, and theslot 31 is of a' length sufficient toaccomplish the loop 38 in a position corresponding to the particular series of openings 35 that are engaged by the tongues 36 of the part 39. When the parts 29 and 30 are assembled, as here shown, a pin 39* which carries the pig-tail I2 is positioned with a drive fit between the loop 38 and the top surface of the part 29, and in this Way the parts are firmly secured together so that the saddle-like member thus formed may be" ap-' plied to a removable'brush portion in the manner above described.

While I have, for the sake of clearness and in order to disclose the invention so' that the same can be readily understood, described and illustrated specific devices and arrangements, I desire to have it understood that this invention is not necessarly limited to the specific means disclosed, but may be embodied in other ways that will suggest themselves to persons skilled in the art. It isbelieved that this invention is new and it is desired to claim it 50 that all such changes as come within the scope of the appended claims are to be considered as part of this invention.

Having thus described my invention, What I claim and desire to secure by Letters Patent is:

1. A brush for dynamo-electric machines, comprising a non-metallic arc resisting renewable portion having a lateral groove at the outer end thereof, a resilient spring clipof conducting material disposed over the outer end of said renewable portion and having depending flexible fingers with inturned ends adapted to engage said groove and serving as the sole means for holding said clip upon said renewable portion, and a flexible pig-tail connection permanently secured to said metallic clip.

2. A brush for dynamo-electric machines, comprising a non-metallic arc resisting renewable portion having half-round grooves extending laterally along the opposit sides thereof, a metallic clip of resilient construction disposed over the outer end of said renewable portion and having depending flexible fingers with involute flanges adapted to engage said grooves and serving as the sole means for holding said clip in electrical contact with said renewable portion, and a flexible pig-tail connection permanently secured to said metallic clip.

3. A brush for dynamo-electric machines, comprising a carbon arc resisting renewable portion having tinned undercut half-round contact surfaces formed in the sides thereof, a saddle-like metallic clip of resilient construction having oppositely disposed depending sides with involute flanges adapted to removably engage said undercut surfaces and make contact with said renewable portion, and a flexible pig-tail connection permanently secured to said metallic clip.

4. A brush for dynamo-electric machines, comprising a non-metallic arc resisting renewable contact portion having undercut contact surfaces formed in the opposite sides thereof, a removable metallic saddle of resilient construction having opposed depending flexible sides with involute flanges adapted to slidably engage said renewable portion at said undercut grooves, said renewable portion having a metallic plating at said undercut groove whereby a metal to metal contact will be provided between said involute flanges and said undercut surfaces, and a flexible pig-tail connection permanently secured to said metallic saddle.

5. A brush for dynamo-electric machines, comprising a renewable commutator engaging portion of carbon having a groove extending laterally along each side thereof, means forming a metallic surface integrally attached to said carbon portion at said grooves, a resilient saddlelike member of tempered beryllium copper having depending sides with inwardly disposed flanges corresponding to the configuration of said ooves and slidable over the outer end of said renewable portion to establish contact therewith, and a flexible current carrying conductor permanently secured at one end to said resilient saddle-like member.

6. A brush for dynamo-electric machines, comprising a renewable commutator engaging portion of arc resisting material having a groove extending laterally along each side thereof, said grooves being arranged in opposed relation, means forming a metallic surface integrally attached to said renewable portion at said grooves, a saddle-like member of resilient material having depending sides with involute flanges at the ends thereof corresponding to the configuration of said grooves and slidable therein to establish contact between said renewable portion and said saddle-like member, and a flexible current carrying conductor permanently secured at one end to said saddle-like member.

7. In a collector for dynamo-electric machines, the combination of a renewable commutator engaging portion of carbon having grooves arranged in opposed relation and extending laterally along each side thereof, a plating of metal forming a contact surface integrally attached to the carbon portion at said grooves, a resilient saddle-like member of tempered beryllium copper having depending sides with inwardly formed contact portions corresponding to the configuration of said grooves and slidable laterally into engagement with the outer end of said renewable portion of carbon, a flexible current carrying conductor permanently secured at one end to said metallic saddle-like member, and a box-like holder for said collector having end walls extending upwardly adjacent the depending sides of said saddle-like member to prevent a displacement thereof when said collector is in operation.

8. In an adjustable means for attaching flexible pig-tail connections to carbon brushes of different thicknesses, the combination of a saddlelike member formed of two parts each having top portions adapted to be secured together and also a depending side portion with oppositely arranged contact-forming surfaces that are adapted to engage the opposite sides of a carbon brush, one of said parts having a series of spaced narrow slots and a single elongated slot formed therein, the other of said parts having a plurality of tongues adapted to engage the narrow slots of said other part and also an upwardly extending loop-forming portion adapted to project through the elongated slot of said other part, and a securing pin adapted to be driven under said upstanding loop-forming portion with its extending ends engaging said slotted part, whereby the opposed contact surfaces of the saddle-like member will be held in a definit fixed relation with respect to each other as determined by the location of they projecting tongues of said one of said parts in the narrow slots of the other of said parts.

JOHN T. BROWN. 

